package org.bouncycastle.jce.provider;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.math.BigInteger;
import java.security.interfaces.DSAParams;
import java.security.interfaces.DSAPublicKey;
import java.security.spec.DSAParameterSpec;
import java.security.spec.DSAPublicKeySpec;

import org.bouncycastle.asn1.ASN1Sequence;
import org.bouncycastle.asn1.DEREncodable;
import org.bouncycastle.asn1.DERInteger;
import org.bouncycastle.asn1.DERNull;
import org.bouncycastle.asn1.x509.AlgorithmIdentifier;
import org.bouncycastle.asn1.x509.DSAParameter;
import org.bouncycastle.asn1.x509.SubjectPublicKeyInfo;
import org.bouncycastle.asn1.x9.X9ObjectIdentifiers;
import org.bouncycastle.crypto.params.DSAPublicKeyParameters;

public class JDKDSAPublicKey implements DSAPublicKey {
    private static final long serialVersionUID = 1752452449903495175L;

    private BigInteger y;
    private DSAParams dsaSpec;

    JDKDSAPublicKey(DSAPublicKeySpec spec) {
        this.y = spec.getY();
        this.dsaSpec = new DSAParameterSpec(spec.getP(), spec.getQ(),
                spec.getG());
    }

    JDKDSAPublicKey(DSAPublicKey key) {
        this.y = key.getY();
        this.dsaSpec = key.getParams();
    }

    JDKDSAPublicKey(DSAPublicKeyParameters params) {
        this.y = params.getY();
        this.dsaSpec = new DSAParameterSpec(params.getParameters().getP(),
                params.getParameters().getQ(), params.getParameters().getG());
    }

    JDKDSAPublicKey(BigInteger y, DSAParameterSpec dsaSpec) {
        this.y = y;
        this.dsaSpec = dsaSpec;
    }

    JDKDSAPublicKey(SubjectPublicKeyInfo info) {

        DERInteger derY;

        try {
            derY = (DERInteger) info.getPublicKey();
        } catch (IOException e) {
            throw new IllegalArgumentException(
                    "invalid info structure in DSA public key");
        }

        this.y = derY.getValue();

        if (isNotNull(info.getAlgorithmId().getParameters())) {
            DSAParameter params = new DSAParameter((ASN1Sequence) info
                    .getAlgorithmId().getParameters());

            this.dsaSpec = new DSAParameterSpec(params.getP(), params.getQ(),
                    params.getG());
        }
    }

    private boolean isNotNull(DEREncodable parameters) {
        return parameters != null && !DERNull.INSTANCE.equals(parameters);
    }

    public String getAlgorithm() {
        return "DSA";
    }

    public String getFormat() {
        return "X.509";
    }

    public byte[] getEncoded() {
        if (dsaSpec == null) {
            return new SubjectPublicKeyInfo(new AlgorithmIdentifier(
                    X9ObjectIdentifiers.id_dsa), new DERInteger(y))
                    .getDEREncoded();
        }

        return new SubjectPublicKeyInfo(new AlgorithmIdentifier(
                X9ObjectIdentifiers.id_dsa, new DSAParameter(dsaSpec.getP(),
                        dsaSpec.getQ(), dsaSpec.getG()).getDERObject()),
                new DERInteger(y)).getDEREncoded();
    }

    public DSAParams getParams() {
        return dsaSpec;
    }

    public BigInteger getY() {
        return y;
    }

    public String toString() {
        StringBuffer buf = new StringBuffer();
        String nl = System.getProperty("line.separator");

        buf.append("DSA Public Key").append(nl);
        buf.append("            y: ").append(this.getY().toString(16))
                .append(nl);

        return buf.toString();
    }

    public int hashCode() {
        return this.getY().hashCode() ^ this.getParams().getG().hashCode()
                ^ this.getParams().getP().hashCode()
                ^ this.getParams().getQ().hashCode();
    }

    public boolean equals(Object o) {
        if (!(o instanceof DSAPublicKey)) {
            return false;
        }

        DSAPublicKey other = (DSAPublicKey) o;

        return this.getY().equals(other.getY())
                && this.getParams().getG().equals(other.getParams().getG())
                && this.getParams().getP().equals(other.getParams().getP())
                && this.getParams().getQ().equals(other.getParams().getQ());
    }

    private void readObject(ObjectInputStream in) throws IOException,
            ClassNotFoundException {
        this.y = (BigInteger) in.readObject();
        this.dsaSpec = new DSAParameterSpec((BigInteger) in.readObject(),
                (BigInteger) in.readObject(), (BigInteger) in.readObject());
    }

    private void writeObject(ObjectOutputStream out) throws IOException {
        out.writeObject(y);
        out.writeObject(dsaSpec.getP());
        out.writeObject(dsaSpec.getQ());
        out.writeObject(dsaSpec.getG());
    }
}
